A Si p-n-p transistor has impurity concentrations of 5´1018, 2´1017, and 1016 cm-3 in the emitter, base, and collector, respectively. The base width is 1.0mm, and the device cross-sectional area is 0.2 mm2. When the emitter-base junction is forward biased to 0.5 V and the base-collector junction is reverse biased to 5V,
a) Calculate the neutral base width
b) Calculate the minority carrier concentration at the emitter-base junction.